Actually - whether they will charge at a high rate of charging when connected in parallel again, depends on their internal resistance and the voltage difference. Many people have attempted to balance-charge by connecting all cells/batteries in parallel without getting a perfect balance, due to the small difference in voltage and resulting low current. For example, I have a pack consisting out of golf cart batteries for 120V (20 x 6V) When I draw 300A then the pack sags up to 30V down, so internal resistance is just under 0.1 Ohm. If I charge them in series and I would connect them in parallel when there is 1V difference between the two halves, there will be a equalization current of about 10A. Of course, with some chemistries the current can be (much) higher, but it is hard to get an overwhelming fault current.
Regarding the picture: - you could get rid of either coil2 or coil3 without problem for the EV system. - you need to make sure that both the remaining coil3 or coil2 and coil4 are open before closing coil1 or you are short-circuiting a half pack. - it would be best to have a fuse in line with each pack, just in case there is a switching error Is this added complexity really the best answer to the savings on the charger current? Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of Michael Kadie via EV Sent: Thursday, March 26, 2015 10:46 AM To: Steve Clunn; [email protected] Subject: Re: [EVDL] charging two parallel packs in series So I drew a really crude wiring diagram. http://goo.gl/kAj5wH Note that it is important the two packs are balanced within a few volts of each other after the series charging. Otherwise when you reconnect them in parallel they will arc across the connector and cross charge at a VERY HIGH AMPERAGE. T-Rex / KD SSI-Racing -----Original Message----- From: Steve Clunn via EV Sent: Thursday, March 26, 2015 7:15 AM To: [email protected] Subject: [EVDL] charging two parallel packs in series >Subject: [EVDL] Open Circuit Voltage Across Contactors I've got two Anderson contacts on my pack, one on the negative side and one on the positive side. So when the key is out of the ignition, the controller and all other components are separated from the traction pack. I currently have a 120V system, with two strings in parallel, because I have a Curtis controller, which has a 144V max. I would, however, like to be able to charge faster with my PFC-30. So my question is, if I reconfigure the packs to be in series for charging, is there any problem, since both contactors will be open? Bill> This could be done safely by leaving one pack ( pack A ) hooked up normally then using two Anderson connectors with your charger being the only thing connected to pack B's battery plus ,chargers neg will go to pack A's neg. Pack B will hook to pack A using a 175amp or bigger Anderson disconnect with pack A's pluses going to pack B's plus and A's neg to B's neg , this will be for driving and parallel charging . Pull the disconnect and plug in a Anderson jumper plug which will connect the A packs positive to the B packs negative and now your are charging in series. If you forget to switch back , no big deal you will just be running on pack A . A few ways to set up these Anderson's , I think the 175 amp Anderson would be big enough . I would have one on pack A and 2 and pack B ( one for series and one for parallel ) The series plug will have its b+ plug going to the B packs neg . shameless plug ,, we sell them but there not on the web site Steve Clunn Merging the best of the past with the best of the future. www.Greenshedconversions.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
